This study focused on kinetics and equilibrium isotherms of mercury biosorption from water using dry biomass of Chlorella vulgaris as biosorbent at pH 5.0. Biosorption tests were performed at 2.0 g/L biomass dosage varying initial Hg concentration from 11.0 to 90.6 mg/L. The Lagergren equation was found to best describe the process, with R2 of 0.984 and specific rate constant of 0.029 ± 0.004 min-1. Although equilibrium data were well fitted by the Dubinin and Radushkevich isotherm (R2 = 0.870; qDR = 16.6 mg/g), important insights on phenomenological events occurring at equilibrium were concurrently provided by the Lamgmuir one (R2 = 0.826; q0 = 32.6 mg/g; KL = 0.059 L/mg). FT-IR analysis confirmed that Hg biosorption took place via physisorption. Since C. vulgaris is a fresh-water microalga that can be easily cultivated anywhere, these promising results suggest its possible use as an effective, low-cost biosorbent to treat industrial effluents contaminated by this metal.
Keywords: kinetics; FT-IR; Mercury biosorption; equilibrium.